These parameters control server-wide statistics collection
features. When statistics collection is enabled, the data that is
produced can be accessed via the pg_stat and pg_statio
family of system views. Refer to Chapter
27 for more information.

track_activities (boolean)

Enables the collection of information on the currently executing
command of each session, along with the time when that command
began execution. This parameter is on by default. Note that even
when enabled, this information is not visible to all users, only to
superusers and the user owning the session being reported on, so it
should not represent a security risk. Only superusers can change
this setting.

track_activity_query_size (integer)

Specifies the number of bytes reserved to track the currently
executing command for each active session, for the pg_stat_activity.query field. The default value is 1024. This
parameter can only be set at server start.

track_counts (boolean)

Enables collection of statistics on database activity. This
parameter is on by default, because the autovacuum daemon needs the
collected information. Only superusers can change this setting.

track_io_timing
(boolean)

Enables timing of database I/O calls. This parameter is off by
default, because it will repeatedly query the operating system for
the current time, which may cause significant overhead on some
platforms. You can use the pg_test_timing tool to measure the
overhead of timing on your system. I/O timing information is
displayed in pg_stat_database,
in the output of EXPLAIN when the
BUFFERS option is used, and by pg_stat_statements. Only superusers can
change this setting.

track_functions
(enum)

Enables tracking of function call counts and time used. Specify
pl to track only procedural-language
functions, all to also track SQL and C
language functions. The default is none,
which disables function statistics tracking. Only superusers can
change this setting.

Note: SQL-language functions that are simple enough to be
"inlined" into the calling query will
not be tracked, regardless of this setting.

update_process_title (boolean)

Enables updating of the process title every time a new SQL
command is received by the server. The process title is typically
viewed by the ps command, or in Windows by
using the Process Explorer. Only
superusers can change this setting.

stats_temp_directory (string)

Sets the directory to store temporary statistics data in. This
can be a path relative to the data directory or an absolute path.
The default is pg_stat_tmp. Pointing this
at a RAM-based file system will decrease physical I/O requirements
and can lead to improved performance. This parameter can only be
set in the postgresql.conf file or on the
server command line.

For each query, output performance statistics of the respective
module to the server log. This is a crude profiling instrument,
similar to the Unix getrusage()
operating system facility. log_statement_stats reports total statement
statistics, while the others report per-module statistics.
log_statement_stats cannot be enabled
together with any of the per-module options. All of these options
are disabled by default. Only superusers can change these
settings.